The present invention relates generally to integrated circuit interfaces, and more specifically to integrated circuit interfaces having current mode drivers.
Integrated circuits typically have dedicated interface circuits to communicate with other integrated circuits and other systems. These dedicated interface circuits are typically interconnected with conductors, commonly referred to as xe2x80x9csignal linesxe2x80x9d or xe2x80x9ctraces,xe2x80x9d that carry signals from one integrated circuit to another. Some signal lines are xe2x80x9cterminatedxe2x80x9d with a termination impedance that approximates the characteristic impedance of the signal line. These terminations can increase communication reliability by reducing unwanted signal reflections on the signal line. When the characteristic impedance of a signal line is uniform across its length, and the termination impedance xe2x80x9cmatchesxe2x80x9d the characteristic impedance of the signal line, signal reflections can be substantially reduced.
Signals that travel from one integrated circuit to another are becoming faster and faster. As signal speeds increase, the effects (unwanted reflections) of poorly terminated signal lines become more pronounced, and proper terminations become more important. In prior systems, signal lines are commonly terminated using external resistors coupled to the signal line outside the integrated circuit. These external resistors can.reduce reflections if chosen carefully, but can also take up a significant amount of space outside the integrated circuits. In systems that include many signal lines in need of termination, external resistors can consume a prohibitively large amount of space.
In addition to consuming space, external resistors typically require a system designer to compromise the quality of the termination. Signal line impedances vary from system to system, and external resistors typically exist at standard impedance values, thereby forcing the system designer to include external resistors that provide a compromised signal line termination.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for alternate integrated circuit interfaces and terminations.